Ken Welter wrote:

  Here is a couple photos of the new coot hull I just pulled out of
the mold, its big, like real big and light weight do to the foam
core, glass and kevlar construction, I have not weighted it yet but
will let you know when I do. Note the second step that I added, it is
create cavitation and to brake surface tension, most race boats today
run multiple steps. The modified mold is in the background.
  Ken

Looks great Ken. I am sure you will be flying again before your know
it. Once you have installed a rotary the second one becomes much easier
I am sure as you know exactly what to do.

Paul Lamar

Question:

"Note the second step that I added, it is

create cavitation and to brake surface tension,"

What would be the effect while flying? How much added drag?

Alfonso Lebron-Berges

Worst case.... dynamic pressure times area. Or if the step is two inches
high by 30 inches wide area is 60 square inches. Or .42 square feet.
At 100 MPH and sea level dynamic pressure is 26 pounds per square foot.
Or 11 pounds of drag. At 147 FPS (100 MPH) and 11 pounds 1600 lb ft/sec 
divided by 550 lb ft/sec that is about 3 HP. Coots don't fly very fast.

Probably less as it is in the boundary layer and you would not be
able to see full dynamic pressure behind the step. One could find out real
quick with a water manometer.

Paul Lamar
 
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